function dcountup(startingdate, baseunit){
  this.currentTime=new Date()
  this.startingdate=new Date(startingdate)
  this.timesup=false
  this.baseunit=baseunit
  this.start()
}

dcountup.prototype.oncountup=function(){} //default action for "oncountup"

dcountup.prototype.start=function(){
  var thisobj=this
  this.currentTime.setSeconds(this.currentTime.getSeconds()+1)
  var timediff=(this.currentTime-this.startingdate)/1000 //difference btw target date and current date, in seconds
  var oneMinute=60 //minute unit in seconds
  var oneHour=60*60 //hour unit in seconds
  var oneDay=60*60*24 //day unit in seconds
  var dayfield=Math.floor(timediff/oneDay)
  var hourfield=Math.floor((timediff-dayfield*oneDay)/oneHour)
  var minutefield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour)/oneMinute)
  var secondfield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour-minutefield*oneMinute))
  if (this.baseunit=="hours"){ //if base unit is hours, set "hourfield" to be topmost level
    hourfield=dayfield*24+hourfield
    dayfield="n/a"
  }
  else if (this.baseunit=="minutes"){ //if base unit is minutes, set "minutefield" to be topmost level
    minutefield=dayfield*24*60+hourfield*60+minutefield
    dayfield=hourfield="n/a"
  }
  else if (this.baseunit=="seconds"){ //if base unit is seconds, set "secondfield" to be topmost level
    var secondfield=timediff
    dayfield=hourfield=minutefield="n/a"
  }
  var result={days: dayfield, hours:hourfield, minutes:minutefield, seconds:secondfield}
  this.oncountup(result)
  setTimeout(function(){thisobj.start()}, 1000) //update results every second
}

var ellabirth=new dcountup("June 20, 2007 00:21:00", "days")

ellabirth.oncountup=function(result){
  var mycountainer=document.getElementById("cpcontainer")
  mycountainer.innerHTML="<span >"+result['days']+"   days,   "+result['hours']+"   hours,   "+result['minutes']+"   minutes &amp;   "+result['seconds']+"   seconds  </span>"
}